The role of steps in the dissociation ofH2 on Mg(0001)

Abstract

The role of steps in the dissociation of molecules on metal surfaces has been extensivelyinvestigated in the past. In particular, both theoretical calculations and experimental results forH2 dissociation on transition metal (TM) surfaces show that steps can significantly increase thereactivity, leading to higher metal–H binding energies and lower activation energies. Herewe have used density functional theory (DFT) with the generalized gradient approximation(GGA) to investigate the role of steps on the Mg(0001) surface in the dissociation ofH2 and the binding of H to the metal surface. Our results follow those found for TM surfacesas far as H adsorption energies are concerned, namely that adsorption energies are highernear the steps. However, we find that the activation energy for the dissociation of hydrogenis hardly affected by the presence of steps, with a DFT–GGA value of 0.85 eV,only marginally lower than the value 0.87 eV found on the flat Mg(0001) surface.